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Apollo 13 Moments of Interest / 141:15:37 Jack Garman predicts LM jettison gimbal lock

« on: August 30, 2024, 03:39:29 pm »

During the LM jettison, in a brief conversation with YAW Will Pressley, Jack Garman warns him that "transience in separation" might cause a CSM gimbal lock to occur. He's referring specifically to oscillations in attitude as a result of the delta-V imparted on the CSM in separation. The deadband isn't as much of a concern since the spacecraft is in a 5-degree deadband; thus, the middle gimbal angle is moving between 10 and 20 degrees from gimbal lock.

Later, one of the AGC support personnel calls the gimbal lock warning, but because his voice on the loop is so faint, it's missed and it's a full 3 or 4 seconds before anyone from the ground brings this to the attention of FLIGHT/CAPCOM. By that point, it's already too late and Swigert has already gone to direct control to correct this, but Garman does take this as an opportunity to remind Pressley of his concerns.

Link:
Before gimbal lock - https://apolloinrealtime.org/13/?t=141:15:37&ch=22
Gimbal lock - https://apolloinrealtime.org/13/?t=141:30:14&ch=22

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Apollo 13 Moments of Interest / 141:02:53 Reed: "I'm gonna jam him back in!" Panic over Lovell's wrong turn

« on: August 30, 2024, 03:11:05 pm »

In "13 More Things That Saved Apollo 13", it notes that Jim Lovell put the Apollo 13 spacecraft 90 degrees out of the desired jettison attitude (LM yaw, CSM/body roll), since LM yaw was an out-of-plane orientation and going to the PAD attitude would have put the spacecraft in gimbal lock. In looking at the air-to-ground and PAO loop, there is no indication that there's any issue with this, as CAPCOM Joe Kerwin reassures Lovell that the yaw isn't critical.

In the trench, it's a much different story.

After Swigert's fantastic P52 which bypassed the need for a sun-moon alignment, there was a frantic effort by both the ground and the crew to get the LM jettisoned. As a result, Kranz never got a formal "go" from GUIDO Ken Russell for the jettison attitude. In the chaos, the "go" came from CONTROL Hal Loden, which created a stir in the trench. GUIDO pointed this out to FIDO Dave Reed and warned him that CDR Jim Lovell was bailing out of the LM, per the air-to-ground. Reed made a remark that would have been unthinkable coming from any other FIDO: "I'm gonna jam him (Lovell) back in!"

What follows is a very confused series of events, and it really benefits to listen to the whole loop from 141:02 to 141:10, as it progresses from the trench bickering and arguing over the safety of the jettison attitude (the normally cool and professional Dave Reed audibly vacillates on whether the attitude is safe), with FAO and CONTROL jumping in to provide their input. In the end, the question is brought to FLIGHT, Gene Kranz, with the eventual determination that they have no choice but to accept the new jettison attitude. Either way, this is arguably the moment of greatest panic throughout the entry prep for the Trench.

FIDO: We need to have Jim take the LM to the FDAI angles that we gave him on the LM jettison pad!
FLIGHT: How far off is he?
RETRO: Flight--he's gonna jettison the service module to the north--I mean, the LM to the north. We don't want him to the north, we want him to the south.

One thing of note about this exchange is that Kerwin asks if the concern is about the impact on the landing point of the atomic fuel cask (as mentioned in the article), but RETRO Chuck Deiterich explains, as he does in the article, that they simply want to ensure that the LM and CSM don't collide in the jettison. This is supported by the fact that Dave Reed later checks the relative motion of both spacecrafts with the new attitude, and verifies that both will be okay.

Link:
FIDO - https://apolloinrealtime.org/13/?t=141:02:53&ch=20
GUIDO - https://apolloinrealtime.org/13/?t=141:02:53&ch=21
CONTROL - https://apolloinrealtime.org/13/?t=141:02:53&ch=57

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Apollo 13 Moments of Interest / 126:41:26 Jack Garman agitated over Mattingly veering off script

« on: July 26, 2024, 06:51:06 am »

During the read-up of the CSM entry checklist to Jack Swigert, Ken Mattingly deviates from the checklist momentarily to talk to Jack Swigert about how to bring the computer out of standby.

AGC specialist Jack Garman, who had already been grousing with Steve Bales earlier in the day about ensuring that the computer procedures were properly detailed, explodes with exasperation upon hearing this, as he believes that Swigert is being fed incorrect information. Even Swigert himself seems to sound confused; as Garman explains to Bales, since the computer would have been powered up for a while by this time and would have already gone to standby, the 37 06 would not come up automatically as Mattingly is claiming.

Later, Garman stalwartly predicts that Swigert is going to get to this point in the checklist and then call down to Houston with a complaint that the computer doesn't work.

Garman later turns out to be correct.

URL: https://apolloinrealtime.org/13/?t=126:41:26&ch=22

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Apollo 13 Moments of Interest / 055:06:23 EECOM Liebergot reveals how high-gain antenna failed

« on: July 04, 2024, 09:17:25 am »

A serious amount of documentation (available here on page 118 of the PDF, and here as a separate document) was churned out by the Test Division in trying to figure out why the high-gain antenna failed to lock up with the Apollo 13 spacecraft during the TV pass at 55 hours. In both documents, the specific cause of the antenna failure was not fully identified, although it did note that it was not a manufacturing defect and that the failure likely occurred after transportation from the manufacturing plant.

EECOM Sy Liebergot, listening in to INCO struggling to lock up the high-gain with the spacecraft, calls up the EPS personnel in his backroom to let them know how the high-gain antenna may have been broken - and it's a surprisingly simple explanation.

Even during the Apollo program, accidents did happen!

Link: https://apolloinrealtime.org/13/?t=055:06:23&ch=16

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Apollo 13 Moments of Interest / 064:16:26 Bob Carlton gives the redline for power and water

« on: July 04, 2024, 08:44:02 am »

During a briefing session by FLIGHT Glynn Lunney on the Black Team shift immediately following the accident, off-duty CONTROL Bob Carlton joins the conversation to give the MOCR flight controllers, and not incidentally Glynn himself, the straight talk on just how austere a power/water profile they will need to adhere to in order to get the crew home safely. This chilling opening dialogue really drives home just how grim the situation was:

CONTROL: Glenn, the guys in the back are running this water profile. Right now it looks like it's coming in real tight, the water itself.
FLIGHT: Yeah? Assuming we stay at this level from now on?
CONTROL: Negative. Assuming we power down post PC2.

Link: https://apolloinrealtime.org/13/?t=064:16:26&ch=50

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Apollo 13 Moments of Interest / 019:19:14 BOOSTER reports to FIDO Greene that S-IVB is tumbling out of control

« on: July 04, 2024, 08:13:12 am »

The BOOSTER engineer (as yet unnamed) reports to a bemused FIDO Jay Greene that it's no longer possible to command to the S-IVB to change its trajectory, and both the guidance platform and computer on board have broken down. He delivers this with report with a demeanor not unlike that of someone whose car has just broken down for the last time.

Later, he reports this to SELECT who is already having difficulty calculating its trajectory due to the noisy Doppler data. They're even more thrilled to discover that the APS (ascent propulsion system) thrusters are still firing and producing rates.

Link: https://apolloinrealtime.org/13/?t=019:19:14&ch=20

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Apollo 13 Moments of Interest / 107:05:24 Exasperated FIDO and RETRO grill CONTROL on SHe tank

« on: June 17, 2024, 08:40:27 am »

CONTROL Larry Strimple is working his second mission in the MOCR after having been backroom support in the LM SSR for several missions. Maroon Flight Milt Windler has just floated the very, very undesirable prospect over the flight loop of having to periodically (every hour on the hour) fire a 10-second ullage of the DPS in order to alleviate the supercritical helium tank. Obviously, this would wreak havoc on the spacecraft's trajectory, since Aquarius is currently on what is essentially a free-return trajectory with no PGNS, no AGS, and very little tracking data.

It seems CONTROL isn't as worried about this as the rest of the flight controllers are, as FIDO Bill Boone and RETRO Tom Weichel give Larry a taste of just how hard it is to be a flight controller during an anomaly situation.

Link: https://apolloinrealtime.org/13/?t=107:05:24&ch=20

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Apollo 13 Moments of Interest / 106:58:21 Jay Greene: "Hey babe, it's time to make another decision~"

« on: May 20, 2024, 11:22:41 am »

The sarcastic, singy-songy (if a bit sleepy) tone of this remark from FIDO Jay Greene to SELECT John Layton really drives home all of the difficult, sometimes hurried, oftentimes no-win choices that the flight controllers had to make, especially from a data and telemetry standpoint. There were several major decisions made over the past two days, including whether to power down the S-BAND transponder, when to power up the ranging, etc., and many of these decisions involved a lot of intense negotiation between dynamics, systems, and data branches. So you can just imagine Greene's elbow on the console as he leans his head on his hand, rolling his eyes, as he has to tell Layton it's time to make yet another decision.

Certainly it's not a trivial decision in this case: From this point in the mission, they have roughly 36 hours until EI (entry interface, the time at which the spacecraft programmatically enters Earth's atmosphere). With new procedures and new checklists that have to be devised, they have to cram simulations of both the LM and CSM, sometimes integrated, into this short time span to ensure that the procedures work in practice as they do on paper.

In order to make the sims work, they need to also simulate the data. One can only imagine the computational requirements for flying an Apollo mission in one floor of the MOCR and simulating the same Apollo mission on a separate floor. The problem that Jay presents to Al is one of timing and logistics. Luckily, they both quickly come to a consensus on what to do.

https://apolloinrealtime.org/13/?t=106:58:21&ch=20

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Apollo 13 Moments of Interest / 125:46:35 TELMU and SURGEON do horse-trading on drinkable water

« on: April 12, 2024, 02:25:50 pm »

As of 125:46:35 GET - still more than 12 hours away from entry interface and splashdown - the CSM is out of potable water in the surge tank, meaning now there are only two ways to get drinking water for the crew: the PLSS, which people are generally hesitant to use in case it's needed as a backup for the LM; and any water remaining in the LM descent tanks.

The conversation between TELMU and SURGEON on the MOCR loop is polite and considered, but there is obvious strain and tension in their voices as they negotiate between two competing needs - the desire to keep the crew alive by having sufficient water to power equipment in the LM, and the desire to keep the crew alive by having sufficient water to avoid dehydration.

Link 1 (SURGEON, 125:46:35): https://apolloinrealtime.org/13/?t=125:46:35&ch=13
Link 2 (SURGEON, 125:52:02): https://apolloinrealtime.org/13/?t=125:52:02&ch=13

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Apollo 13 Moments of Interest / 123:11:26 Flight dynamics assistant too tired to continue

« on: April 12, 2024, 02:00:27 pm »

A flight dynamics assistant during the Gold team shift just prior to re-entry at 123:11 GET calls up FIDO Bill Stoval essentially to ask if he can go home early due to fatigue. He had been off his game all night, including a really serious blunder earlier in the evening that resulted in GUIDO Bales and RETRO Spencer arguing over whether a REFSMMAT stored in the RTCC was the same one as earlier in the morning. It had been stored incorrectly.

Amidst all of the technical jargon on the FIDO loop, clips like these really show the human impact that the Apollo 13 incident had on the flight controllers who were trying to manage the situation on the ground, many of them not getting enough sleep or just outright pulling all-nighters.

Link: https://apolloinrealtime.org/13/?t=123:11:26&ch=20

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Apollo 13 Moments of Interest / 116:58:07 Trench creates the Flight Dynamics re-entry checklist

« on: March 22, 2024, 12:20:34 pm »

Apollo geeks and flight dynamics nerds brace yourselves - this is going to be your lucky day.

This is by far the highlight of the FIDO loop. During the Black Team shift starting at around 110-112 GET, FIDO Dave Reed, RETRO Chuck Deiterich and GUIDO Ken Russell are manning the trench along with YAW Will Pressley. This will also be the same group of personnel that works the White Team's shift during re-entry.

Dave, a stickler for organization and "doing the right thing", sets aside time with Chuck and Ken to draft a re-entry checklist for the flight dynamics team during the hours leading up to entry interface. This is required due to the massive amount of work needing to be done in a very short timespan, getting both the CSM reactivated and aligned, the service module and LM jettisoned, and the midcourse correction required to stay in the corridor.

What follows from this point on is truly remarkable: an unbroken three-way discussion that goes on for over an hour, essentially a planning meeting taking place on a live MOCR loop. During this time, Dave has backup personnel respond to inquiries from other flight controllers so that his team can focus on drafting the checklist. Presumably, he got permission from Lunney to do this since even FLIGHT avoids bugging him with questions. (AFD is not so lucky when he tries later on.)

RETRO: https://apolloinrealtime.org/13/?t=116:58:07&ch=19
FIDO: https://apolloinrealtime.org/13/?t=116:58:07&ch=20

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Apollo 13 Moments of Interest / 089:30:00 Trench can't keep track of all the meetings going on

« on: February 21, 2024, 08:53:05 am »

It is now 8:43AM local time. FAO Bob Lindsey is reaching out to RETRO (but instead getting FIDO Bill Boone) to ask whether there's going to be an 8am re-entry meeting. Boone doesn't know about that - but he does know about Bill Tyndall's data priority meeting, and he wonders if perhaps that's what FAO means?

Link: https://apolloinrealtime.org/13/?t=089:30:00&ch=20

Apollo 13 was on its way back to Earth. Although the PC+2 abort burn was executed as correctly as could be under the circumstances (with subsequent tracking indicating that a MCC5 would still be necessary), flight control still had one major problem to contend with: re-entry - all the activities that would be needed in the last six hours of flight.

One of the most key aspects of Apollo 13 after the oxygen tank disaster is the total, industry-wide mobilization that occurred in order to solve rapidly-developing problems that urgently needed an answer by a certain timeframe. From one end of the Manned Spacecraft Center to the other, there was one practice that was a near-constant throughout the mission: Meetings. Meetings. Meetings. Sometimes planned, but more often improvised, all to tackle different problems, all vacuuming up different flight controllers with all of their varying levels of expertise.

This is why when listening to the FD loops after the abort burn, you sometimes can hear up to 3 or 4 different officers manning one station during a single shift. They frequently had to be swapped out as managers such as Gene Kranz, Bill Tyndall, Neil Hutchinson and Jerry Bostick yoinked controllers and brought them from one meeting to the next.

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Apollo 13 Moments of Interest / 061:27:28 Burn time freakout: "Is he loaded correctly?!"

« on: February 16, 2024, 02:44:11 pm »

Within three minutes of the free return burn, FLIGHT Glynn Lunney suddenly notices that the wall clock in the MOCR is off by a large amount. Once RETRO Tom Weichel provides a countdown from his retro clock indicating the time left before the burn, Glynn suddenly becomes a lot more animated over the loop.

It was shortly thereafter determined that the wall clock had been improperly set by the comm staff, and that both the spacecraft and the retro clock were properly synchronized to the burn time.

Link: https://apolloinrealtime.org/13/?t=061:27:28&ch=19

As an addendum, later before the PC+2 burn, FIDO Bill Stoval (also in the MOCR at the time of the free return burn, sitting next to Bill Boone) reminds Bobby Spencer to check the wall and retro clock to make sure both are aligned - "I'd hate to get zapped on that one again."

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Apollo 13 Moments of Interest / 110:32:09 GUIDO gives the first words on CSM alignment techniques to CAPCOM

« on: February 05, 2024, 09:53:53 am »

This is prompted by a question from Jim Lovell, who wanted to know how the command module will be aligned for re-entry, particularly with the LM still hanging onto it. As far as I know, these are the absolute first ever words spoken over the Flight Director loop regarding the actual techniques involved. It comes across as a somewhat informal conversation, with GUIDO Gary Renick essentially walking through the process and CAPCOM Jack Lousma repeating his own interpretation of the words back to him (off the loop), to make sure that his understanding is correct for when he passes it up to the crew.

There's a lot of background noise on the GUIDO and CAPCOM loops, so for the sake of ease on the ears, this is just the isolated flight director loop.

LINK: https://apolloinrealtime.org/13/?t=110:32:39&ch=50

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General Discussion / Frank Borman

« on: November 09, 2023, 05:03:00 pm »

And now Frank Borman. One of the most accomplished astronauts, including CDR of Apollo 8, has passed away at the age of 95.

https://www.wsj.com/business/airlines/frank-borman-who-led-historic-flight-around-the-moon-in-1968-dies-at-age-95-489afa09

Ad Astra. *